Lift the fan shroud and fan straight up and out. Take care to disconnect the indicated connector

Remove the heatsink clamps with a flathead screwdriver and do the same for the other side.

Lift off the heatsink and remove the 4 screws of the CPU board.

There are 4 pins: remove the 3 pins near the RAM but not the pin nearest You.

You are now ready to slide gently (and without ANY difficult) the motherboard. Lift up and the game is done.